The subject invention relates to an improved printing plate for printing a linear bar symbol code on material, and in particular, a printed plate especially adapted for printing a symbol code on corrugated paperboard material.
In order to expedite the handling and distribution of boxed products, such as food products, packaged goods, etc., a symbol code may be employed and disposed on the shipping container for the products. As an example, usually a corrugated paperboard carton is employed as an outer carrier or container for a plurality of cans of foodstuffs, and to expedite the processing and shipment of the carton of foodstuffs, a symbol code may be printed on the outer corrugated paperboard carton. The symbol code generally encodes eleven information digits which are in human-readable form, and a linear bar arrangement that is encoded in machine-readable form. Usually twelve encoded linear bar characters are provided consisting of eleven informational characters plus one check character. The linear bar encoded characters are boarded by a start pattern on the left side, and by a stop pattern on the right side. Usually a seven-module "light" area precedes the "start" pattern, and also follows the "stop" pattern of the linear bar characters, and furthermore, the linear bar symbol is separated into halves by a central field separator pattern. The latter affords means whereby the linear bar symbols may be machine-read by two scans, each of which covers at least one half of the linear bar code arrangement. The result of those two scans is then processed through suitable "reading" equipment in order to "read" the linear bar portion of the symbol code.
Prior art printing plates for printing a linear bar symbol code are generally made of rubber and have a thickness on the order of 0.250 inches. The prior art printing plate generally includes a plurality of raised, spaced, portions, or bars which, of course, have the dimensions of the desired linear bars of the code for the symbol code to be printed. The printing plate also includes a plurality of raised numerals which print the human-readable digits, and generally the printing plate is mounted on a cylindrical drum. As the drum rotates, the printing plate comes into contact with the carton or container to be printed, and the symbol code is printed thereon.
Prior art printing plates for printing a symbol code have several shortcomings, especially when used in conjunction with containers or cartons made of a corrugated paperboard material. For example, the only part of the printing plate usually coming in contact with the corrugated container to be printed, and thus the part of the plate bearing the full pressure of the drum as the symbol code is being printed, is the relatively thin raised linear bar portions and digits of the printing plate. In practice, it has been found that because the linear bar portions are made of rubber or plastic material, they are compressible, and the compression of the opposite ends of the linear bars gives rise to expansion and distotion of the individual bars, and hence of the overall symbol code. It will be appreciated that distortion of the linear bars or incomplete printing thereof may be critical in that if the correct dimensions of the desired linear code are not accurately reproduced, a non-scan or possibly an incorrect product information scan may result.
The shortcomings of the prior art printing plates may even be more acute when the material upon which the symbol code is to be printed is a corrugated paperboard. More specifically, it has been known that the printing pressure, which is concentrated in the very thin, raised linear portions of the printing plate, and in the digits on the printing plate, may cause a relatively deep impression in the printed material, especially in those regions of the corrugated paperboard wherein the overlay sheets bridge the corrugated intermediate portion of the paperboard. In such case, the resulting impression may be distorted and could result in partial crushing of the paperboard in the region of the distribution symbol code.
Accordingly, it is an object of the subject invention to provide a new and improved printing plate for printing a linear bar distribution symbol code having a more uniform distribution of pressure.
It is a further object of the subject invention to provide a printing plate having the above characteristics in which the degree of distortion after repeated use of the plate is significantly reduced.
It is a further object of the invention to provide a new and improved printing plate having the above characteristics which, when used for printing a symbol code on corrugated paperboard minimizes crush or damage to the paperboard.